Note: Descriptions are shown in the official language in which they were submitted.
CA 022~401~ 1998-ll-12
Index 870 - 655.00696
Modine
Patent
HEAT BATTERY
Field of the Invention
This invention relates to so called latent heat batteries or accumulators.
More specifically, it relates to a heat battery that is ideally suited for, but not limited
to, vehicular applications.
o Background of the Invention
Recent years have seen an increased interest in so called heat batteries for
vehicular use. Such heat batteries typically include a heat storage medium whichusually, but not always, is a phase change material such as a salt or a high specific
heat single phase material. The battery includes an internal heat exchanger
through which engine coolant is circulated. To charge the battery with heat, hotengine coolant that is heated during engine operation is passed through the heatexchanger and its heat rejected to the heat storage medium. Subsequently, the
heat may be utilized to heat the passenger compartment or to immediately providewarm coolant to the engine for the purpose of reducing emissions and easing start-
Up wear by circulating now cold coolant through the heat exchanger to be warmed
first and then passed to the engine. The stored heat may also be used to operatethe vehicle defroster for immediate defrosting. At this time, heat will be rejected by
the heat storage medium to the coolant to warm the same; and will thereafter be
rejected to the engine to warm it.
In cold climates, the use of such heat batteries in vehicles is particularly
desirable because they provide a means whereby hot coolant for use in a vehicle
CA 022~401~ 1998-11-12
'
heater is immedi~tely available upon entry into the vehicle and/or is available to
warm the engine long prior to the time at which the engine would warm as a result
of intemal combustion occurring therein. The benefits of immediately being able to
warm the passenger compartment are obvious. Those skilled in the art will also
recognize that internal combustion engines produce the greatest quantity of
undesirable emissions during start up. Cold or cool engines do not promote
effective combustion of fuel and as a consequence, hydrocarbon emissions from
uncombusted fuel may be substantial.
Prior attempts to provide commercially viable heat batteries have not proved
o all together successful. In one such attempt, the heat storage medium was a salt
that could change between the solid and liquid phases in the temperature range of
operation to absorb or reject the latent heat of fusion of the salt to maximize heat
storage capability. Unfortunately, the material employed was highly corrosive which
led to a number of obvious diffficulties.
More recently, it has been proposed to utilize magnesium nitrate hexahydrate
containing a small amount of lithium nitrate. This material works well but when
placed in a heat battery formed of aluminum, gases are generated which must be
vented.
It has therefore been proposed in European patent application EPO 770,844,
the entire disclosure of which is herein incorporated by reference, to provide ameans of venting the chamber of the heat battery containing the heat storage
medium to avoid pressure build up. It is therein proposed to utilize a check valve
that is soldered or otherwise located in an opening in the jacket defining the so
called salt chamber (the chamber that contains the heat exchanger and the heat
storage medium) which may then be connected to a vent opening to the coolant
circulation system. While this approach has generally avoided the problem causedby pressure build up, it has not been 100% successful in so doing.
In particular, when a heat battery is mounted in a vehicle, it is subjected to
all the forces that are encountered when the vehicle accelerates, decelerates, goes
around a corner or skids on a skid pad resulting in substantial centrifugal forces, as
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well as the force of gravity as the vehicle travels over uneven or nonlevel terrain.
In such situations, the heat storage ~ate~ial, if it is a phase change material, is most
always in the liquid phase as a result of being heated by operation of the vehicle
engine. The heat storage material, being in the liquid phase, may splash around
within the salt jacket and onto the valve inlet. In some instances, it is conceivable
that it could even immerse the valve inlet. If the salt is permitted to forrn a meniscus
on the valve inlet, when the battery vents, the salt may enter the valve.
Entry of the heat storage material or salt into the check valve has been
known to disable the check valve either resulting in its inability to open to relieve
o excess pressure or, more likely, in being unable to close, which may allow the
interior of the salt jacket to freely vent to and from the cooling system, an
occurrence that is undesirable.
The present invention is directed to overcoming one or more of the above
problems.
Summary of the Invention
It is the principal object of the invention to provide a new and improved heat
battery. More particularly, it is an object of the invention to provide a new and
improved heat battery of the type including a container for housing a salt or other
phase change material that may be in the solid phase at a relatively low ambienttemperature and in the liquid phase at temperatures on the order of the operating
temperature of a vehicular cooling system. A heat exchanger is located within the
container and includes a coolant flow path through which vehicular engine coolant
may be flowed to exchange heat with the phase change material. A body of
insulation surrounds the container to provide insulation for the same. In the usual
case, this will be provided by a second container that surrounds the first container
in generally spaced relation, but in some instances, the second container can beomitted so long as some means of insulating the first container is provided. Coolant
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inlet and outlet connections extend through the insulating " ~ate~ ial and the container
to the heat exchanger so as to deliver coolant thereto to exchange heat with thephase change material.
In a preferred embodiment, the container has a top wall flanked by two
s spaced side walls that are intended to be located along a generally horizontal line
transverse to the longitudinal axis of a vehicle in which the heat battery is to be
installed. A vent is provided for the salt container which includes an outlet as well
as an inlet in the top wall of the first container.
According to one facet of the invention, the inlet to the vent is located
o generally centrally of the sp~ced side walls so as to ~,i"i"~i~e contact of the phase
change material with the vent.
According to another facet of the invention, a cup-shaped baffle having a
downwardly facing opening is disposed within the first container and surrounds the
vent inlet. The baffle further assists in maintaining the phase change material away
from the vent.
According to still another facet of the invention, a two piece baffle is provided
for the vent path inlet and includes a baffle piece loc~ted in the first container about
the inlet and a fixture piece on the outside of the first container, usually in the space
between the two containers. The pieces have interengaging threads extending
through an opening in the top wall of the salt container so as to be self fixturing for
brazing within the battery.
According to still another facet of the invention, a vent opening is provided
in the first container as generally alluded to previously and a check valve is
connected to the vent opening for allowing fluid flow out of the first container but
substantially prevents fluid flow in the reverse direction. A conduit having a
passage of capillary size is connected to the check valve oppositely of the ventopening. According to this facet of the invention, even a small discharge of gas is
sufficient to clear the vent pass~ge defined by the capillary passage in the conduit.
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According to still another facet of the invention, a fixture, including a valve
receiving pocket, is in fluid communication with the vent opening. A check valve is
movably received in the pocket and is openable to allow fluid flow from the vents opening but substantially prevents fluid flow in the reverse direction. The check
valve, when in the pocket, sealingly engages the fixture. Means are provided forbiasing the check valve into the pocket and into sealed engagement therewith. The
biasing means is such as to be overcome by a predetermined pressure at the vent
opening so that the check valve will begin to move out of the pocket and the sealed
engagement therewith to relieve the pressure at the vent opening in the event that
the check valve or capillary tube becomes blocked. This arrangement provides a
safety factor in the event the check valve becomes inoperable.
According to still another facet of the invention, both a first inner container
and a second outer container surrounding the first container are employed and ans opening is located in the second container and is aligned with the vent. A conduit
extends between the vent and the opening in the second container. A check valve
assembly for the vent is removably received in the conduit and means are provided
for locating the check valve assembly at a predetermined position within the conduit.
According to this facet of the invention, the check valve may be removed from the
assembly to be serviced if required.
According to still another facet of the invention, a filter is provided for the vent
opening and is made of a material that is not wetted by the phase change material.
In a preferred embodiment, the filter material is a porous
polytetrafluoroethylene material.
According to still another facet of the invention, the vent opening is located
in the upper surface of the first container and a second container surrounds the first
container and has a vent opening therein. A vent conduit is connected to the first
container vent opening and extends through the second container vent opening.
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The vent conduit is connected and sealed to the second container at the second
conlainer vent opening and is formed of two tube sections. A bellows interconnects
the two tube sections to provide fluid communication between them. This facet ofthe invention compensates for a n ,;salignment between the two openings and evenmore importantly, provides a means of accommodating differential thermal
expansion and contraction and relative movement between the two containers.
According to still another facet of the invention, a vent conduit connects the
vent opening in the first contail-er and extends through the second container to the
exterior thereof. An enlarged reservoir is connected to the conduit and is located
o exteriorly of the second container. A vent is disposed in the upper surface of the
reservoir. This facet of the invention provides a means whereby vented liquid orcondensate is captured in the reservoir while vented gas may be vented through the
reservoir to the exterior of the vehicle.
According to still another facet of the invention, the vent for the first container
includes a vent conduit extending away from a vent opening therein. A check valve
is located in the conduit in close proximity to the vent opening so that stored heat
in the phase change material will warm the check valve to prevent condensation or
freezing of moisture therein.
In a preferred embodiment, the conduit is located in a space between two
containers including the first container so that heat in the phase change material will
warm the conduit to minimize condensation therein as well as to prevent freezing.
According to still another facet of the invention, the heat battery has a cup
shaped baffle with a downwardly facing opening within the first container as
mentioned previously. A quantity of the phase change material is disposed in thefirst container to substantially, but not completely, fill the same. The quantity of
phase change material is such that the baffle will not be contacted by the phasechange material when the heat battery is stationary and in its normal operating
position. The volume of the cup shaped baffle is such that if the downwardly facing
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opening is covered by the phase change material as a result of acceleration,
deceleration, centrifugal forces or the encountering of uneven terrain, pressure in
the first container will pressurize the phase change material into the baffle a
distance insufficient to reach the vent inlet before the downwardly facing opening
s is uncovered by the phase change material to prevent phase change material from
being delivered to the vent.
Other objects and advantages will become apparent from the following
specification taken in connection with the drawings.
o Description of the Drawings
Fig. 1 is a somewhat schematic sectional view of a heat battery made
according to the invention;
Fig. 2 is an enlarged exploded, sectional view of a vent employed in the heat
battery;
Fig. 3 is an enlarged sectional view of the vent with the components in
assembled relation;
Fig. 4 is a further enlarged, fragmentary view of part of the vent components;
Fig. 5 is a sectional view of a valve housing employed in the invention.
Description of the P.efer.. ,d Embodiment
An exemplary embodiment of a heat battery is illustrated somewhat
schematically in Fig. 1 and will be described herein in the context of a heat battery
intended for use in vehicular applications. However, it will be understood that the
heat battery is not so limited, but may be used with efficacy in most any type of
environment requiring the use of a heat battery or a temporary thermal storage
device.
Referring to Fig. 1, the heat battery includes a first or internal container 10,sometimes referred to as a salt jacket, which is surrounded, in spaced relation by
.. ... . ~ . .
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an outer, or so called insulating, jacket 12 or second container. The space 14
between the jackets 10 and 12 will usually be subject to a high vacuum as is well
known and additionally will be typically filled with an insulating material as, for
example, a material known in the art as "aerogel" powdered insulation.
s In some instances, the outer jacket 12 may be eliminated, but in all cases,
the inner jacket 10 will be surrounded by some sort of insulating material or
structure.
The inner jacket 10, in the embodiment illustrated, is in the form of a sheath
16 sealed to the periphery of opposed headers 18, 20 of a heat exchanger,
generally desiynaled 22. As is well known, flattened tubes 24 extend between theheaders 18, 20 and may have serpentine fins 26 or other fins extending between
adjacent ones of the tubes 24. Tanks 28 and 30 close off headers 18 and 20
respectively.
In one case, two of the structures just described will be located in generally
side by side relationship and a cross over tube 32 will interconnect the spaces
between corresponding ones of the headers 20 and tanks 30. Alternatively, in a
single structure as described, a baffle (not shown) in the tank 28 and header 18construction separating the inlet and outlet ports may be used.
Each of the tanks 28 includes a port 34 connected to a U-shaped tube 36.
One leg 38 of the U-shaped tube is in the space 14 while the other leg 40 is on the
exterior of the jacket 12. Both of the tubes 36 (only one of which is shown)
terminate at an external fixture block 42 which may be brazed to the jacket 12. One
of the tubes 36 will serve as an~inlet for engine coolant through the heat exchanger
22 and the other will serve as an outlet for the engine coolant. Hoses interconnect
the vehicle cooling system and the fixture block 42.
The jacket 10 and its connection to the header components 18, 20 of the
heat exchanger 22 define a closed space which will typically be almost completely,
but not quite, filled with a salt or phase change material. Specifically, with the jacket
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10 stationary and level, it will be filled to a level 50 with a salt of the type that will
undergo a phase change between the liquid and the solid phases over a typical
range of operating values for engine coolant, i.e., a range from about -200C up to
130~C. In a preferred form of the invention, the phase change material, which
serves as a heat storage material, is magnesium nitrate hexahydrate containing asmall amount of lithium nitrate as is known. The various components described
thus far are made of metal, preferably aluminum, and as a consequence, the phasechange material reacts to form corrosive gases which must be vented to prevent
pressure build up in the battery.
o To avoid pressure build up, the invention includes a vent system, generally
designated 52, to prevent the build up of pressure within the heat battery and to
dispose of the vented mate~ial in a harmless fashion. As seen in Fig. 1, the venting
system 52 includes an inlet end, generally designated 54, in the jacket 10 generally
centrally thereof between the side walls as defined by the headers 18 and 20. The
inlet end 54 is in the upper or top surface 56 of the salt jacket 10. This of course
assumes installation in a vehicle or the like with the surface 56 uppermost. In this
connection, it is desirable that the headers 18,20 and tanks 28, 30 be spaced along
a generally horizontal line which is transverse to the longitudinal axis of the vehicle
in which the heat battery is installed.
The venting system 52 also includes an outlet end, generally designated 57,
which is on the exterior of the insulation jacket 12. As seen in Fig. 3, the outlet end
57 is connected via a suitable conduit to an enlarged reservoir 58 which in turnincludes a gas vent 60 in its top- or upper surface that may discharge to the exterior
of the vehicle. The enlarged reservoir 58 is typically sized so as to be sufficiently
large to hold all liquid discharged to the venting system 52 over, for example, a ten
year period. Assuming relatively normal usage of the vehicle, (it is thought) that the
volume of the reservoir 58 should thus be such as to hold approximately 75 ml ofliquid to achieve this goal. That is to say, it is expected that 75 ml of liquid will be
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discharged into the reservoir 58 over a ten year period. However, as a practicalmatter, much of such liquid will evaporate and the vapors thereof will exit via the
vent 60 from the reservoir 58 in any event.
Figs. 2 and 3 illustrate the venting system 52 in exploded and assembled
relation, respectively. The inlet end 54 of the system 52 includes a generally cup
shaped bame 60 of a generally cylindrical configuration. The same includes an inlet
opening 62 which faces downwardly toward the level 50 (Fig. 1 and 4) of the salt in
the jacket 10. The upper end of the bame 60 is threaded as at 64.
The salt jacket includes a vent opening 66 through which the threaded end
68 of a cup shaped fixture 70 passes. The bame 60 is threaded onto the threaded
end 68 of the fixture 70 and the arrangement is such that the two are self fixturing.
That is to say, the two may be brought into proper assembled relation with the
jacket 10 so as to be brazed in place during a subsequent assembly operation.
The cup shaped fixture 70 includes a side opening 72 which receives a
pocket defining structure 74 having an internal pocket 76.
Oppositely of the pocket 76, the structure 74 mounts a filter 78 within the
interior of the cup shaped fixture 70. The filter 78 is made of material that will not
be wetted by the salt contained within the jacket 10. One material that may be used
is a porous polytetrafluoroethylene. If desired, the filter 78 may be in the form of a
plug of sintered polytetrafluoroethylene granules. Alternatively, it may be made of
a film like material of the type sold under the registered trademark "Gortex." In this
case, it may be in the form of a small, condom-like sheath fitted over the end of the
male end 144 at a location within the cup shaped fixture 70.
Preferably, the filter 78 has a "salt break through pressure differential" of atleast about 3 psi. This valve will prevent the salt from passing through the filter 78
to the valve system 52 with an appropriate safely factor. In one embodiment, thesalt break through pressure differential is 13 psi using a polytetrafluoroethylene filter
having a pore size of 0.2 microns.
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Near one side, the insulation jacket 12 includes an opening 80 which
receives a nipple 82 having threads 84 on an end thereof exterior of the insulation
jacket 12. A thin walled stainless steel tube 86 extends between the pocket defining
structure 74 and the nipple 82 and is sealed to both. The stainless steel tube 86 is
made up of a relatively short segment 88, and a relatively long segment 90. The
two are interconnected by a bellows formation 92.
Optionally, and as seen in Fig. 4, the bellows 92 may be enclosed in a
housing 94. The housing 94 may be in the form of a metallic foil wrapped around
the bellows 92. The purpose of the housing 94 is to prevent particles of the
insulating material from entering the sp~ces between the convolutions defining the
bellows 92 where the particles could interfere with its operation. In this regard,
when the insulation is introduced into the space 14, it is customary to subject the
entire heat battery to substantial agitation to cause the insulation material to settle.
During such agitation, it is possible that individual granules of insulation could
become lodged in the bellows 92 and interfere with its operation. The purpose ofthe bellows is two fold. The first purpose is to allow for slight degrees of
" ,isalig"ment between the pocket defining structure 74 and the nipple 82. A second
and more significant purpose is to accommodate the fact that as the jackets 10 and
12 are subjected to different temperatures, they will expand and contract at different
rates and the bellows 92 compensates for thermally induced stresses as a result of
such differential expansion and contraction. The bellows also compensates for
stress when the containers undergo relative movement particularly during the
shaking of the insulation fill.
Desirably, because the tube 86 is thin walled, at several locations along its
length (only one of which is shown) the same may be provided with annular or
circumferential stiffening ribs 100.
A valve assembly, generally designated 102, is located within the tube 86.
The valve assembly includes a number of components including a valve housing
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104 as shown in Fig. 5, a self contained check valve 106, which is of conventional
construction and preferably of the ball and spring type, and an elongated thick
walled tube 108. The tube 108 has a central p~ss~e 110 of capillary size, i.e., on
the order of 1 mm in diameter.
s Near the outlet end 57 of the venting system 52, a snap ring 112 is located
on the tube 108 and a compression coil spring 114 abutted there-against. An
intemally threaded cap 116 may be located over the end 56 and threaded onto the
threads 84 on the nipple 82 to abut an end 118 of the spring 114 to compress thesame as will be seen, with the end 56 extending through a bore 120 and an end ofthe cap 116.
Retuming to the pocket defining structure 74, the same includes an intemally
stepped bore which in part defines the pocket 76. A relatively small diameter
section 122 receives the filter 78. A relatively large diameter section 124 receives
the short section 88 of the outer tube 86.
An intemmediate diameter section 126 movably and removably receives the
valve housing 104.
A shoulder 128 defines the interface of the large diameter section 124 and
the intermediate diameter section 126 of the pocket 76 and serves as a valve seat.
Referring to Figs. 4 and 5, the valve housing 104 has an internal, axial
passage 130 that opens to the small diameter section 122 of the pocket 76.
Oppositely of the passage 130, the valve housing 104 includes an enlarged cavity132 into which the check valve 106, which is of conventional construction, is
received. An end of the tube 108 is force fitted into the cavity 132. The
arrangement is such that flow is pemmitted out of the salt jacket 10 to the end 57 but
iS substantially inhibited in the reverse direction, dependant on the leak rate of the
check valve 106.
It is important to observe that the valve housing 104 also has a stepped
exterior including a relatively small diameter section 134 which is sized to snugly fit
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within the intermediate diar"eter se-,1iol l 126 of the pocket 76. About the cavity 132,
the valve housing 104 has a relatively larger diameter section 136. The larger
diameter section 136 is somewhat smaller than the large diameter section 124 of
the pocket 76 and is separated from the smaller diameter section by a shoulder 138
which will abut the shoulder 128 of the pocket 76 during normal operation.
An outwardly facing annular groove 140 is located in the small diameter
section 134 of the housing 104 to receive an elastomeric O-ring seal 142. The O-ring seal 142 establishes a seal against the intermediate diameter section 126 of
the pocket 76 during normal operation as can be seen in Fig. 4.
The check valve system 102 is completed by a small diameter protuberance
or male end 144 (Fig. 5) which receives the filter 78 and mounts it within the small
diametersection 122.
When the valve system 102 is assembled as illustrated in Fig. 3, it will be
seen that the cap 116 compresses the spring 114 which, acting against the snap
ring 112, provides a biasing force on the tube 108 to bias the same toward the left
as viewed in Fig. 3. This has the effect of urging the valve housing 104 to the left
as viewed in Fig.3 to the point where the shoulder 138 halts further such movement
by engagement with the shoulder 128 on the pocket 76. At this point, the O-ring
132 will be sealed against the intermediate diameter section 126 of the pocket 76.
In the usual case, the valve 106 be will selected to open at a pressure differential
of approximately 10 psi so that upon the generation of pressure within the salt
jacket 10, the check valve 106 will open and allow the pressure to be dischargedto the capillary passage 110. ~n this regard, the capillary passage 110, from one
end to the other, has such a small volume, that even a small discharge is suffficient
to completely clear the passage 110 of condensed liquids.
In the event the check valve 106 becomes inoperative and refuses to open
to discharge built up pressure, the pressure will act against the left hand end of the
valve housing 104. As the pressure builds up, the valve housing 104 moves to the
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right as viewed in Figs. 3 and 4 against the bias of the spring 114.
At the point where the O-ring seal 142 moves to the right of the valve seat
defined by the step 128 in the pocket 76, the seal between the valve housing 104and the pocket 76 will be lost, allowing the pressure to discharge about the body of
the valve housing 104 into the space between the thin walled tube 90 and the thick
walled tube 108 to relieve pressure. This pressure may vent to the atmosphere
through the opening 120 in the cap 116 about the end 57 of the tube 108. Typically,
the spring 114 is selected and the components located relative to one another toprovide suffficient compression that the safety valve thus defined by the seal 142,
o the valve housing 104, and the step 128 in the pocket 76 will open at about a 22 psi
pressure differential.
Another important feature of the invention is the location of the valve 106 in
close proximity to the vent opening 66 in the salt jacket 10. When the same is in
close proximity as indicated, conduction of heat from the hot salt via the salt jacket
10, the cup shaped fixture 70 and the pocket defining-structure 74 will assure that
the valve 106 is sufficiently hot that condensation of any discharge, which is rich in
water, will not occur within the valve 106.
Furthermore, the location of the venting structure 52 between the salt jacket
100 and the insulation jacket 12 similarly tends to assure that the same remainswarm to prevent such condensation therein. At the very least, the heat present will
prevent any condensation that occurs from freezing at low ambient temperatures
to plug the vent system 52.
It will also be observed that the valve system 52 is at an angle slightly greater
than 90o to the longitudinal axis of the cup shaped baffle 60. In one embodiment,
an angle of about 97O is selected.
As a further point, the volume, location and shape of the interior of the cup
shaped baffle 60 are such as to provide a "burp" effect for venting pressure when
the level of salt is not as shown at 50, but rather, covers the inlet opening 62 to the
14
CA 022~401~ 1998-ll-12
baffle 60. The cup shaped baffle 60 is preferably an inverted, nominally cylindrical
cup whose opening 62 is of sufficiently large diameter that it cannot be closed by
a meniscus of molten salt. The central axis of the bame 60 should be, as close as
possible, on a line perpendicular to the normal level 50 of the salt. The baffleopening 62 should be at a level where contact with the salt is at a minimum for the
typical operating cycle of the vehicle.
Volume of the cup shaped baffle 60 is determined by five factors including
(1 ) the volume of the connecting vent tubing and associated hardware system forthe relief valve 104, 106, (2) the maximum anticipated pressure head of the salt,
associated with the worst case, off-attitude operation, (3) the baffle aspect ratio, (4)
the relief valve leakage rate, and (5) the cracking pressure and flow characteristics
of the check valve. Salt head pressure is defined as the average vertical heightdifferential existing between the bottom plane of the opening 62 and the molten salt
level in the worst-case situation, multiplied by the density of the salt.
Baffle volume must be sufficiently large to insure that salt, regardless of
baffle attitude, will not rise in the cup-shaped bafffle to a level where it could enter
the vent tube 72.
The baffle aspect ratio is the ratio of the length of its central axis to its
diameter, and should be maximized, but not to the extent diameter becomes small
enough to allow a meniscus to form.
The check valve leakage rate must be small enough to assure that gas
leakage for a worst case maneuver of the vehicle will not permit the salt level to rise
to a cross section small enough to allow a meniscus to form.
As alluded to previously, the components will typically be formed of aluminum
unless otherwise noted above. The components are generally brazed together and
braze clad material will be located on the components where they are to be brazed
together.
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In ~dditiol " welds may be employed in various locations as, for example, at
the connection between the pocket defining stnucture 74 and the cup shaped fixture
70. In addition, the cup shaped fixture 70 and the cup shaped baffle 60 may be
respectively welded at their interfaces with the salt jacket 10. Similarly, the nipple
582 will typically be welded into the opening 80 in the insulation jacket 12.
In summary, a heat battery made according to the invention will provide one
or more of the following features:
1. The use of a cup shaped baffle to prevent the salt from accessing a
venting system.
o2. The use of a cup shaped baffle and a cup shaped fixture threaded
together to provide self fixturing of the baffle and its connection to the venting
system.
3. The use of a nonwettable filter on the intake side of the venting system
to prevent the salt from entering any substantial distance into the venting system.
154. The use of a removable valve and/or valve housing to allow servicing
of the valve and filter.
5. The use of a bellows in the venting system to compensate for
misalignment and eliminate thermal stress and stresses resulting from relative
movement.
206. The use of a housing about the bellows so as to prevent insulation
from interfering with operation of the bellows.
7. The use of a capillary passage in the venting system so that even
small discharges of pressurized-gas are capable of clearing condensation from the
vent passage.
258. The incorporation of a safety valve feature that allows venting of the
salt jacket in the event the check valve normally employed for such venting fails.
9. The location of the vent in the center of the top of the salt jacket where
it is less likely to come into contact with liquid salt during acceleration, deceleration,
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centrifugal force effects, etc. on the vehicle on which the heat battery is installed.
10. The use of an enlarged reservoir on the vent system to capture any
liquid discharged or any vapor condensate discharged from the system.
11. The sizing of the interior volume of the baffle 60 so as to achieve the
5"burp" feature described previously .
12. The location of the valve 106 is in close proximity to the inlet opening
so that it will be warmed sufficiently to prevent condensation thereat and/or prevent
freezing of such condensate as may occur.
